Aluminium oxide is impermeable and, unlike the oxide layers on many other metals, it adheres strongly to the parent metal. If damaged mechanically, aluminiumâs oxide layer repairs itself immediately.
Saliva helps remove oral waste and cavity-causing bacteria, protects teeth from decay by neutralizing harmful acids, and helps re-mineralize tooth enamel. Saliva also keeps oral tissues healthy by preventing infection by controlling bacteria and fungi in the mouth.
There's a slew of bacteria floating around in your mouth, but it's generally harmless. Since people have different eating habits in different places, you might think an American's saliva might look a lot different from, say, a South African's. Saliva contains more DNA than blood because of all of the oral bacteria. 2  Most common type of bacteria in saliva is Streptococcus, in a mostly harmless form. 3  Saliva spreads molecules to the taste receptors on the tongue.